The colonies formed were counted using a colony counter and number of colony forming units (cfu) were calculated by using the formula adopted by

Break Down the Problem

1. Identify the key term: Colony Forming Units (CFU).
2. Understand the context: The use of a colony counter for counting colonies.
3. Determine the need for the formula to calculate CFUs.

Relevant Concepts

1. Definition of CFU: It is a unit used to estimate the number of viable bacteria or fungal cells in a sample, which can form colonies.
2. Common formula used for calculating CFUs: $\text{CFU} = \frac{\text{Number of colonies counted}}{\text{Dilution factor} \times \text{Volume plated (in liters)}}$

Analysis and Detail

1. Count the number of colonies: Using the colony counter, tally the colonies observed on the agar plate.
2. Determine the dilution factor: This is based on how the original sample was diluted before plating.
3. Measure the volume plated: This is the volume of sample that was placed on the agar plate, typically noted in liters.

Verify and Summarize

1. Ensure the counts are accurate and that the dilution factor and volume are correctly noted.
2. The final estimate of CFUs provides an important insight into the microbial load of the sample being tested.

Final Answer

To calculate the CFUs from your experiment, apply the derived formula with your specific values: $\text{CFU} = \frac{\text{Number of colonies counted}}{\text{Dilution factor} \times \text{Volume plated (in liters)}}$ This method accurately reflects the quantity of viable microbes in the sample.